According to the National Center for Health Statistics of the Centers for Disease Control and Prevention, about 12 percent of women (over 7.3 million) in the United States between the age 15-44 suffer from various fertility disorders, defined as difficulty getting pregnant or carrying a baby to term. Treatment of female infertility is therefore an important objective among health care professionals.
In placental mammals, each reproductive cycle consists of two phases: the follicular phase and the luteal phase. During the follicular phase, follicles undergo a maturation process and produce one or more ovum (also referred to as egg or oocyte). The release of mature egg(s) is called ovulation, a point that defines the transition from the follicular phase to the luteal phase. A successful conception requires the timely encounter of sperm and a mature egg. The ability of accurately predicting the time of ovulation is therefore highly beneficial in terms of providing a time frame to perform insemination with enhanced success rate. On the other hand, the ability of assessing oocyte maturation state in a female is also highly beneficial in the context of in vitro fertilization (IVF), a procedure that requires the extraction of eggs from maturing follicles from a female and is directly impacted in its success rate by the quality of the eggs. For the purpose of IVF, the current protocol for determining the time to carry out the steps of promoting final maturation of the eggs (by administration of human chorionic gonadotropin, or hCG, to the female) and harvesting eggs involves ultrasound, CT-scan, and some estimation, the method is therefore in need of improvement in both accuracy and efficiency.
Because of the high prevalence of female infertility and limitations in the current IVF technologies, there exists a need for new, effective, and convenient methods for assessing oocyte maturation and timing ovulation in reproductive medicine. The present invention addresses this and other related needs.